RFR: 8342530: Specifying "@Nx" scaling level in ImageStorage should only load that specific level

[Lukasz Kostyra]

On Thu, 15 May 2025 20:18:04 GMT, John Hendrikx <jhendrikx at openjdk.org> wrote:

>> modules/javafx.graphics/src/main/java/com/sun/javafx/iio/common/ImageTools.java line 166:
>> 
>>> 164:         return true;
>>> 165:     }
>>> 166: 
>> 
>> 1. Is looking for a slash going to be compatible on all platforms?  Where is the path string coming from?
>> 2. Catching `NumberFormatException` to "check" if something is a number is bad form
>> 3. It will allow `@0x` and `@-1x` etc...
>> 4. Consider using a regular expression, it is much more concise and intended for this kind of matching
>> 
>> Here's a regular expression for this:
>> 
>>     Pattern SCALED_PATTERN = Pattern.compile(".*@[1-9][0-9]?x(\.[^\.]+)?");
>>     
>> The above will match any path that ends with `@` followed by a number from 1 to 99, followed by an `x`, optionally followed by an extension that does not contain a dot.  No need to check for slashes.
>
> If you want you can even return the scale with a slightly altered pattern:
> 
>      private static final Pattern SCALED_PATTERN = Pattern.compile(".*@([1-9][0-9]?)x(?:\.[^\.]+)?");
>      
> Then do:
> 
>      Matcher matcher = SCALED_PATTERN.matcher(path);
>      
>      if (matcher.matches()) {
>           return Integer.parseInt(matcher.group(1));  // can't throw NumberFormatException, number is validated by pattern
>      }
>      
>      return 0;  // there was no scale

>Is looking for a slash going to be compatible on all platforms? Where is the path string coming from?

My assumption was that other parts of ImageTools use this assumption so here it would be okay as well. `getScaledImageName` right above this method assumes so (although there it might not matter as much).

Regex might be a better fit for this, I agree.

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PR Review Comment: https://git.openjdk.org/jfx/pull/1809#discussion_r2092390883